Localization for electrocardiographic mapping

Abstract

A system (10) can localize an object in a patient's body. The system (10) can include a pulse generator (18 or 30) configured to provide a localization signal to at least one electrode that is fixed to the object in the patient's body. A sensor array (22) can be configured to detect an electrical field produced in response to the localization signal and provide respective sensor signals. A map generator (42) can be configured to reconstruct electrical signals based on the respective sensor signals and geometry data representing a geometric relationship between patient anatomy and the sensor array. A location calculator (50) can determine a location where the localization signal was applied based on the reconstructed electrical signals.

What is claimed is: 
     
       1. A system to localize an object in a patient's body, the system comprising:
 at least one electrode fixed to the object in the patient's body; 
 a pulse generator configured to generate a localization signal comprising a subthreshold electrical signal and provide the localization signal to the at least one electrode, the subthreshold electrical signal having energy insufficient to stimulate electrical conduction in tissue of the patient's body; 
 a sensor array configured to detect an electrical field produced in response to the localization signal and provide respective sensor signals; and 
 a processor configured to:
 retrieve geometry data stored in memory, the geometry data representing a geometric relationship between patient anatomy and the sensor array; 
 reconstruct electrical signals based on the respective sensor signals and the geometry data; and 
 determine an absolute location where the localization signal was applied based on comparing amplitude and frequency characteristics of each of the reconstructed electrical signals with respect to the localization signal. 
 
 
     
     
       2. The system of  claim 1 , wherein the localization signal further comprising a supra threshold electrical signal, the supra threshold electrical signal having energy sufficient to stimulate electrical conduction in tissue of the patient's body. 
     
     
       3. The system of  claim 1 , further comprising an output generator configured to provide output data representing a graphical display of a heart of a patient that includes an indicator at the absolute location where the localization signal was applied. 
     
     
       4. The system of  claim 3 ,
 wherein the object is one of a catheter or pacing lead; and 
 wherein the output generator is configured to:
 generate a graphical display of the heart of the patient as an electrocardiographic map based on the reconstructed electrical signals; 
 superimpose a first visual indicator on a location of the electrocardiographic map to indicate the absolute location where the localization signal was applied; and 
 superimpose a second visual indicator on the electrocardiographic map to reflect movement of the catheter or the pacing lead relative to the heart of the patient. 
 
 
     
     
       5. The system of  claim 1 , further comprising a cardiac stimulation system configured to deliver therapy to a therapy site in the patient's body corresponding to a location on a heart of the patient's body, the at least one electrode being affixed to a selectively moveable element of the cardiac stimulation system, at least one of the pulse generator and the cardiac stimulation system being configured to provide the localization signal to the at least one electrode. 
     
     
       6. The system of  claim 5 , further comprising an output generator configured to provide output data representing a graphical display of the heart, the graphical display of the heart including an indicator at the absolute location where the localization signal was applied, the indicator being presented at a fixed location in the graphical display of the heart to identify the therapy site. 
     
     
       7. The system of  claim 5 , further comprising an output generator configured to provide output data representing a graphical display of the heart, the graphical display of the heart including an indicator at the absolute location where the localization signal was applied, the indicator being moveable in the graphical display of the heart commensurate with a current location of the selectively moveable element of the cardiac stimulation system. 
     
     
       8. The system of  claim 5 , wherein the cardiac stimulation system comprises one of an ablation therapy system and a pacing therapy system. 
     
     
       9. The system of  claim 1 , further comprising a high-pass filter configured to filter the respective sensor signals to extract signal content corresponding to the electrical field produced in response to the localization signal. 
     
     
       10. The system of  claim 1 , wherein the pulse generator is configured to supply the localization signal to include a combination of the subthreshold electrical signal and a supra threshold signal applied at different times, the supra threshold electrical signal having energy sufficient to stimulate electrical conduction in tissue of the patient's body. 
     
     
       11. The system of  claim 1 , further comprising a cardiac stimulation system configured to control delivery of therapy to a therapy site based on the determined absolute location. 
     
     
       12. The system of  claim 11 , wherein the cardiac stimulation system comprises one of an ablation therapy system and a pacing therapy system.